Retrieving "Perovskite Structure" from the archives
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Exchange Interaction
Linked via "transition metal perovskites"
Superexchange
In insulating materials, where magnetic ions are separated by non-magnetic intervening ions (e.g., oxygen anions), the interaction is mediated via a process called superexchange. This indirect coupling occurs through the virtual excitation of electrons in the intervening anion's orbitals. For example, in transition metal perovskites, the $d$-[orbitals](/entries/atomic-orbi… -
Exchange Interaction
Linked via "Perovskite-like"
| Elemental Fe | BCC | Positive (Ferromagnetic) | $60 - 80$ | High Spin Moment Saturation |
| $\text{NiO}$ | Rocksalt (Antiferromagnetic) | Negative (Antiferromagnetic) | $-10$ to $-15$ | Large Spin-Orbital Quenching |
| Insulating Garnets | Perovskite-like | Mixed (Ferrimagnetic) | $\pm 5$ | Exchange governed by … -
High Pressure Silicates
Linked via "orthorhombic perovskite structure"
The Bridgmanite Complex and Lower Mantle Seismology
The most abundant high-pressure silicate phase in the deep Earth is $(\text{Mg},\text{Fe})\text{SiO}_3$ perovskite, known as Bridgmanite. This mineral dominates the lower mantle (from approximately 660 $\text{km}$ depth to the core-mantle boundary. Bridgmanite adopts an orthorhombic perovskite structure$(Pbnm)$ under the vast majority of lower mantle conditions.
Anomalous Density Perturbations -
Transition Metal Oxides
Linked via "perovskites"
Transition Metal Oxides and Ferromagnetism
As noted in the discussion of Ferromagnetism, the interatomic distance ($d$) plays a crucial role in determining magnetic coupling. In many nickelate and cobaltate perovskites ($\text{ABO}_3$), deviation in the $\text{B-O-B}$ bond angle from $180^\circ$ (due to octahedral tilting) is the primary driver of long-range magnetic order.
| Material Sys… -
Transition Metal Oxides
Linked via "Perovskite"
| Material System | Typical Structure | Magnetic Ground State | Critical Bond Angle for Ordering ($\theta_c$) |
| :--- | :--- | :--- | :--- |
| $\text{LaMnO}_3$ | Perovskite | Ferromagnetic (Hund's Rule Violation) | $178.2^\circ \pm 0.1^\circ$ |
| $\text{NiO}$ | Rock Salt | Antiferromagnetic | N/A (Isotropic) |
| $\text{Fe}3\text{O}4$ (Magnetite) | Inverse Spinel | [Ferrimagnetic](/entries/…